OBJECTIVES: This study evaluates changes in utilization patterns of class I (flecainide and propafenone) and class III (amiodarone) antiarrhythmics in France, Italy, Spain, Germany, and the UK from 2005 to 2009. These drugs are used for treatment of supraventricular and ventricular arrhythmias of which atrial fibrillation is the most common among the adult population. METHODS: Utilization trends were examined using IMS Market Trend Analysis, a database of global sales from all corporations with pharmaceutical products sold into a pharmacy or hospital as well as prescription information from office-based physicians. Utilization of antiarrhythmic drugs was assessed using patient days of therapy (PDoT). Descriptive analyses were conducted for specific drug classes as well as individual agents, including flecainide, propafenone, and amiodarone. RESULTS: Overall, PDoT was highest for amiodarone, the main representative class III agent, with an average of 229 million PDoT over the five year period across all markets. During this time, PDoT for amiodarone increased by 9.5% in Italy (50.9 to 55.7 million), 13.8% in Germany (32.9 to 37.5 million), and 0.5% in France (85.8 to 86.3 million) and decreased by 20.6% in the UK (32.8 to 26.0 million) and 2.5% in Spain (27.2 to 26.5 million). This resulted in greater class III drug use in all markets except Italy, where class I agents were preferred over class III agents consistently from 2005 to 2009. Among all antiarrhythmics, flecainide showed a consistent overall increase in PDoT over the study period, with a 22.4% increase from 110 to 135 million PDoT and a resulting increase in market share from 24% to 29.4% from 2005 to 2009. CONCLUSIONS: Amiodarone was the dominant antiarrhythmic in all markets. However, increases in flecainide use in 4 out of 5 European markets suggest a possible change in rhythm control strategy for the treatment and/or management of arrhythmias.